1. Field of the Invention
The present invention relates to a sheet glass bending apparatus for pressing a sheet of glass, which has been horizontally delivered from a heating furnace, to a bent configuration, and thereafter tempering the bent glass sheet by quenching.
2. Description of the Relevant Art
There are known various sheet glass bending apparatus by which a sheet of glass, which has been horizontally fed from a heating furnace, is pressed to a bent shape and then tempered by quenching. These known sheet glass bending apparatuses are generally classified into two groups. The sheet glass bending apparatus in one group are of the one-stage type in which a sheet of glass is pressed to a bent shape and tempered by quenching in one location. The sheet glass bending apparatus belonging to the other group are of the two-stage type which includes a tempering stage located downstream of a pressing stage.
The two-stage-type sheet glass bending apparatuses are disclosed in Japanese Patent Publication No. 61-44816 published Oct. 4, 1986, Japanese Laid-Open Patent Publication No. 62-270429 published Nov. 24, 1987, and Japanese Patent Publication No. 62-30136 published June 20, 1987, for example.
According to the apparatus shown in the first and second publications, a sheet of glass is pressed to a bent shape between a ring mold, serving as a lower mold, and an upper mold, in or outside of a heating furnace, and then the bent glass sheet is transferred onto another ring mold and fed to a quenching stage.
According to the apparatus disclosed in the third publication, a single ring mold is integrally fixed to a feed jig, which is reciprocally moved between a pressing stage and a quenching stage to move the ring mold between these stages.
The apparatus disclosed in the first and second publications are made up of a large number of parts since different ring molds are employed in the pressing and quenching stages, respectively. When a sheet of glass is transferred from one ring mold to the other, the peripheral edge of the glass sheet tends to be cracked or distorted.
The apparatus shown in the third publication are made up of a relatively small number of parts because one ring mold is shared by the two stages. However, the feed jig to which the ring mold is integrally fixed is liable to become deformed since it is reciprocally moved between the pressing stage which is kept at a higher temperature and the quenching stage which is kept at a lower temperature. Therefore, the ring mold may be deformed by any such deformation of the feed jig.
The present invention has been made in an effort to effectively solve the above problems of the conventional sheet glass bending apparatus.